How fast is the WidgetLayout renderer? A live FPS benchmark

Since 0.6.0 RazorConsole renders through the WidgetLayout pipeline by default (see what's new in 0.6.0 and the WidgetLayout guide). Instead of a synthetic micro-benchmark, we built a real RazorConsole app that redraws itself as fast as it can and shows its own frame rate on screen.

The terminal above is not a recording: it is a live RazorConsole component (a trimmed-down version of examples/FpsBenchmark) running in your browser through WebAssembly and rendered with the WidgetLayout pipeline. Browser numbers will be lower than a native terminal because WASM runs on a single thread.

What the app measures

The component calls StateHasChanged in a tight loop, so every iteration runs a full Razor render → WidgetLayout measure/arrange → terminal write. Two numbers are shown:

Metric	Meaning
Render FPS	Component render passes completed per second by the WidgetLayout pipeline.
Drawn FPS	Calls Spectre.Console received to write a frame to the terminal (counted by a small `IAnsiConsole` wrapper). Closer to what the user sees, but still not the monitor refresh rate.

Both also show average frame time, frame count, peak and average-since-start.

Run it yourself

dotnet run --project examples/FpsBenchmark -c Release
dotnet run --project examples/FpsBenchmark -c Release -- --rows 40   # heavier tree

Press Ctrl+C to exit. --rows controls how many animated progress rows are on screen, so you can see how frame rate scales with UI size.

Results

In a native run (12 rows, 100x24 terminal, .NET 9, Release, Windows ConPTY inside a VM) the app sustained roughly 2,800 Render FPS (about 0.4 ms per frame) and ~800 Drawn FPS. Numbers vary a lot with the terminal emulator, hardware and row count, so treat them as an order of magnitude, not a guarantee. Terminals themselves typically paint at 60-240 Hz, so the pipeline is far from being the bottleneck for typical TUIs.

Note

The benchmark deliberately runs without any frame limiter. Real apps only render when state changes.

Takeaways

WidgetLayout comfortably renders well beyond display refresh rates for ordinary screens.
The example makes regressions easy to spot: run it before and after a change and compare the on-screen numbers.
Source: examples/FpsBenchmark.